The impact of threat of shock on memory for threat-irrelevant information: Evidence for a role of reduced semantic organization.

Research into the effects of acute anxiety on episodic memory has produced inconsistent findings, particularly for threat-neutral information. In two experiments, we tested the hypothesis that anxiety induced by threat of shock can interfere with the use of semantic-organizational processes that benefit memory. In Experiment 1, participants viewed and freely recalled two lists of semantically unrelated neutral words, one encoded in a threatening context (threat blocks) and one encoded without threat (safe blocks). As predicted, significantly fewer words were recalled during threat than safe blocks. Moreover, free recall patterns following threat blocks showed lower levels of semantic organization as assessed using a "path length" measurement that considers the semantic distance between pairs of consecutively recalled words. Both effects unexpectedly interacted with block order, such that they primarily reflected improved recall and increased semantic organization from the first to the second block in participants who received the threat block first. Experiment 2 used semantically related word lists to reduce potential impacts of task experience on semantic organization. Free recall was again less accurate and showed longer (less organized) path lengths for threat than safe blocks, and the path length effect no longer interacted with block order. Moreover, threat-induced changes to path lengths emerged as a mediator of the relation between physiological effects of threat (increased skin conductance) and reduced subsequent memory. These data point to semantic control processes as an understudied determinant of when and how acute anxiety impacts episodic memory.

Strengthening spatial reasoning: elucidating the attentional and neural mechanisms associated with mental rotation skill development.

Spatial reasoning is a critical skill in many everyday tasks and in science, technology, engineering, and mathematics disciplines. The current study examined how training on mental rotation (a spatial reasoning task) impacts the completeness of an encoded representation and the ability to rotate the representation. We used a multisession, multimethod design with an active control group to determine how mental rotation ability impacts performance for a trained stimulus category and an untrained stimulus category. Participants in the experimental group (n = 18) showed greater improvement than the active control group (n = 18) on the mental rotation tasks. The number of saccades between objects decreased and saccade amplitude increased after training, suggesting that participants in the experimental group encoded more of the object and possibly had more complete mental representations after training. Functional magnetic resonance imaging data revealed distinct neural activation associated with mental rotation, notably in the right motor cortex and right lateral occipital cortex. These brain areas are often associated with rotation and encoding complete representations, respectively. Furthermore, logistic regression revealed that activation in these brain regions during the post-training scan significantly predicted training group assignment. Overall, the current study suggests that effective mental rotation training protocols should aim to improve the encoding and manipulation of mental representations.